Accessory for metal cutting machines



June 10, 1958 J. R. KNOWLES ACCESSORY FOR METAL CUTTING MACHINES Filed Feb. 17, 1955 FIGS INVENTOR. JOSEPfi ussgm. KNQW s :ATT RNEY United States Patent 2,837,972 ACCESSORY FOR METAL CUTTING MACHINES Joseph Russell Knowles, London, England, assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware Application February 17, 1955, Serial No. 488,952

1 Claim. (Cl. 90-11) to facilitating the cutting operation by cooling and lubrication, to reduce wear on the tool and improve the finish of the work. The cutting edge of the tool becomes highly heated in use, but since it is shielded by a continuously formed chip of metal being removed from the work, an overhead stream of coolant such as is usually employed flows over the chip and is deflected so that it bathes the tool at some distance back of the cutting edge, little of it reaching the region of highest heat where it is most needed. Nevertheless, both the chip and tool shank are sufficiently hot to produce irritating smoke on contact with the liquid, and the emission of smoke is frequently so profuse that exhaust systems and various other costly installations are required for alleviation of the nuisance. Where a thin, high speed jet of the fluid is projected upwardly from beneath the tool into the wedge-shaped clearance space between the tool and work, that is, from the under or cut side of the chip, the smoke problem is heightened for here the fluid penetrates effectively to the cutting edge which is at maximum temperature and consequently more smoke is produced.

While it is to :be understood that my invention is not limited in its application to the system last referred to, it is described in such relation for purposes of illustration.

Generally speaking, the present invention provides a means for evacuating smoke from within a bubble-like curtain of flowing liquid which surrounds both the cutting end of the tool and the contiguous portion of the work.

A tube which projects into the confined space is connected 7 to a suction means and serves to draw ofl the smoke as rapidly as it is formed. Where the curtain is completely closed and in the form of a bubble, or even where it is parted in flow over some projection on the machine, or is torn by chips thrown outwardly from the work, an additional tube terminating near the cutting end of the tool may be employed to admit air which serves the dual purpose of assisting in cooling the tool and in preventing inward collapse of the liquid wall under suction.

The invention is shown in the accompanying drawings wherein,

Figure l is a side view, partly in vertical section, showing the invention applied to a lathe and used in association with both an overhead stream of coolant and an upwardly projected, thin jet of the coolant.

Figure 2 is a bottom view of the liquid distributor.

Figure 3 is a side view, partly in vertical section, showing a modified form of the invention in which the smoke eduction pipe is centrally located and a plurality of pipes carry overhead streams of coolant to the tool.

Referring more particularly to the drawings, and first to Figure l, a pipe from which oil or other cutting 2,837,972 Patented June 10, 1958 short distance of the frusto-conical member 12 thereby providing a circular slit orifice 16 at the periphery of the cap.

A cutting liquid supply pipe 17, which may be a branch of pipe 10 leading from a single source, enters the cap 15. Another pipe 18 passes through the cap 15 and the frusto-conical member 12, and connects with a pump or other suction creating device (not shown).

In order to avoid collapse of the confining liquid curtain 19 when suction is applied, and especially if the curtain closes at bottom in bubble form, air is admitted to the enclosed space through a pipe 20 which passes through the cap and -frusto-conical member and extends to a low point within the curtain adjacent the cutting tool 11. The flow of air around the cutting tool thus assists in cooling chip 21 over which the large, low pressure stream of liquid discharges. Cooling of the cutting edge of the tool is, however, principally effected by a small, high speed jet of the cutting liquid which is discharged in upward direction from nozzle 22 through the clearance space between the tool and work piece 23. This jet strikes with high impact effect in the region of extreme heat and with accompanying generation of smoke and vapors. These are confined within the enveloping liquid curtain and are sucked away through pipe 18, being thereupon displacmi by air which is admitted through pipe 20. The direction of flow is shown by arrows in the drawings.

In the modified form of invention shown in Figure 3 the central pipe 24, which passes through the tubular extension 13 of frusto-conical deflector 12, serves as the smoke eduction conduit, such pipe being connected by a T-fitting 25 to an angularly disposed pipe 26 in which an injector nozzle 27 is mounted. Fluid flowing from the nozzle 27 draws the smoke into pipe 24 and entrains it in the fluid which is discharged in the direction of the arrow, thereby creating suction within the liquid envelope 19 and drawing in air through breaks which may occur in its lower portion where the liquid flows over the machine and work piece, especially if the liquid has low surface tension and lacks a tendency to draw into bubble shape.

In this form of the invention, as in that previously described, the primary application of cutting fluid is by the small high speed jet projected from nozzle 22 to the cutting edge of tool 11. Larger streams, in addition, flow downwardly over the chip 21, these being discharged through tubes 28 and 29 which extend through the liquid distributor and terminate within the enclosed space closely adjacent the tool.

I claim:

In a smoke suppressing system for machine tools having a downwardly flaring liquid distributor from which a curtain of liquid flows to surround the end of the cutting tool and the contiguous portion of a work piece, the combination therewith of a smoke eduction pipe extending through the distributor inwardly of its periphery and ter minating within the space confined by the liquid curtain, and a second pipe extending through the distributor inwardly of its periphery for admitting air to the space confined by the liquid curtain, said second pipe terminating nearby the cutting tool.

(References on following page) References Cited in the file of this patent 2,716,914 Pigott Sept. 6, 1955 UN STATES PATENTS 2,716,915 Bibel p 1955 2,093,478 Partsch Sept. 21, 1937 OTHER REFERENCES 2,361,861 Masowich Oct. 31, 944 5 Hi-Iet System for Increasing Tool Life, by R. J. S.

Pigott and A. T. Colwell. Pages 23-24 relied on. 

